this is a probability 2 question

4) a) The lifetime of a printer costing 200 is exponentially distributed with mean 2 years. The manufacturer agrees to pay a full refund to a buyer if the printer fails during the rst year following its purchase, and a one-half refund if it fails during the second year. If the manufacturer sells 100 printers, how much should it expect to pay in refunds? (15p) b) If X has a normal distribution with mean 1 and variance 4, the P(X2-2X58)=